Kodomo no Hi (Children's Day)

Tango originally meant the first 'horse day' of the month; the fifth day of the fifth month became fixed as the date because go (five) sounded like the number. In China the day was one of misfortune in the hot and unhealthy season, warded off with fragrant, medicinal plants such as sweet flag (shobu) and mugwort. At the Heian court, sweet flag was hung from the eaves and worn as a charm.

In the samurai age the day acquired a martial character. Shobu, 'sweet flag', is a homophone of shobu 'martial spirit' and shobu 'contest', and its sword-shaped leaves suited a warrior ethos. By the Edo period the shogunate had made Tango one of the five official festivals, samurai households displayed armour, banners and weapons for their sons, and merchant families imitated them with paper carp and dolls. In 1948 the Act on National Holidays renamed the day Kodomo no Hi and extended it to girls as well as boys.

Carp streamers go back to the Edo period, when commoners, who were not allowed to fly the banners of samurai families, hung carp instead. The image comes from a Chinese legend: a carp that swims up the waterfall known as the Dragon Gate on the Yellow River turns into a dragon, a symbol of perseverance and success in life, recalled in the phrase toryumon, a 'gateway to success'.

A typical set has a five-coloured streamer, the fukinagashi, at the top, followed by a large black carp (magoi), a red carp (higoi) and smaller carp in blue and other colours for the children. A popular children's song identifies the black carp with the father; the red carp was later associated with the mother. Large koinobori displays over rivers, such as those in Tatebayashi in Gunma or along the Shimanto River in Kochi, have become spring attractions.

Indoors, families with sons set up gogatsu ningyo, 'May dolls': miniature suits of samurai armour, helmets (kabuto) or figures of legendary heroes. The helmet protects the head and so stands for protection of the child's body. Popular figures include Kintaro, a boy of enormous strength raised in the mountains, and Shoki, the Chinese demon-queller. As with the hina dolls of March, the displays are often a gift from grandparents for a child's first Tango, hatsuzekku.

On the evening of 5 May many households and public baths float bundles of sweet flag leaves in the bath water, a custom called shobu-yu. The leaves' strong scent was believed to drive away evil and illness, and some people tie them around their heads for health. Despite the common English translation 'iris bath', the plant is Acorus calamus, sweet flag, not the ornamental hanashobu iris.

Two sweets are tied to the day. Kashiwa mochi, rice cakes filled with sweet bean paste and wrapped in an oak leaf, are more common in eastern Japan; because the oak does not shed its old leaves until new ones have grown, it symbolises an unbroken family line. Chimaki, rice dumplings wrapped in bamboo or other long leaves, came from China and remain more common in Kansai.

Children's Day is the last of a cluster of spring public holidays: Showa Day on 29 April, Constitution Memorial Day on 3 May, Greenery Day on 4 May and Children's Day on 5 May. Together with weekends they form Golden Week, one of the three peak travel periods in Japan alongside the New Year and Obon. Trains, flights and accommodation are heavily booked, and popular sights are crowded, while many offices close.